The present invention relates to a method of and an apparatus for performing a weather resistance test. More particularly, the invention is concerned with a method of and apparatus for performing a weather resistance test capable of producing, in a short time, test results having close correlation to actual degradation which is caused on a composite material having a base member of a metal, an inorganic material or an organic material and a coating layer of an organic material, e.g., a plastic when such a composite material is left in natural environment including corrosive substances.
In general, weather resistance of plastics and materials coated with plastics is tested by a weather resistance testing apparatus as specified by JIS (Japanese Industrial Standards) B 7751-7754. Usually, this testing apparatus employs a light source such as a carbon arc lamp or a xenon lamp for generating light rays which are applied to the test samples to promote the degradation thereby enabling the test to be finished in a short time.
In general, structures in seashore areas are exposed to air which is rich in salt, while offshore structures are held in corrosive condition due to contact with sea water. Thus, structures on seashores and offshore structures are exposed to much severe condition as compared with structures in environment which do not contain salty air. Furthermore, in industrial areas where there are many factories, structures are under severe conditions as they are often subjected to acidic rain. The ordinary weather test apparatus mentioned above, therefore, cannot perform promoted test results with good correlation to actual degradation, when the material to be tested is a composite material composed of a metallic substrate and a coating plastic, as in the cases of materials used in structures on seashore areas, offshore structures, ships and fishery equipments, as well as structures in industrial areas.
A composite weather resistance testing apparatus has been known in which a brine spray process is combined with functions of ordinary weather meter such as light irradiation and dew condensation to enable evaluation of resistance to salty environment. A marine exposure promotion testing apparatus is also known in which, as disclosed in Japanese Utility Model Laid-Open No. 55-105153, the tested material is subjected to light irradiation, brine spray and strain.
The known composite testing apparatus and marine exposure promotion testing apparatus, however, can provide only a small ultraviolet irradiation intensity, e.g., 6 mW/cm.sup.2, due to the use of a carbon arc amp or a xenon lamp as the light source. In addition, the speed of degradation of the tested material is too low and the test results do not show close correlation to actual degradation, due to the fact that the test operation includes only the testing processes such as light irradiation, brine spray, dew condensation and generation of strain.